Learn about this topic in these articles:

association with Allomyces

...these organic substances are actually sex pheromones, chemicals produced by one partner to elicit a sexual response in the other. In
Allomyces (order Blastocladiales) a pheromone named
sirenin, secreted by the female gametes, attracts the male gametes, which swim toward the former and fuse with them. In some simple fungi, which may have gametangia that are not differentiated...